This invention relates to ultrasonic receiving transducers, and especially to the combination of an electrostatic transducer and signal processing circuitry in a single monolithic circuit and to the fabrication of such transducers as a unique component during the processing of a monolithic integrated circuit.
Ultrasonic imaging requires an array of ultrasonic sensing elements capable of detecting a pattern of ultrasonic waves impinging upon its surface. The received echo signals from the sensing elements are amplified and electronically processed so that an image can be conveniently displayed on a viewing device. Current practice requires the sensing elements to be fabricated separately from the electronic circuitry, with each element connected by a discrete wire to the processing circuits or otherwise separately connected. Fabrication of the ultrasonic sensor and electronic processing circuitry in a single monolithic circuit will significantly reduce the difficulty in fabricating the array and make possible the manufacture of ultrasound systems and arrays with a larger number of sensing elements.